And what is my point? First, Neil deGrasse Tyson IS DA BOMB! (that is a good thing) Second, I know he only had like 30 seconds to explain the tides. However, he fell into one of the classic blunders. The most famous is never get involved in a land war in Asia, but only slightly less know is to not try and explain the tides in such a short time.

Neil’s explanation was essentially that the tides are caused by the moon. Here is essentially what he said:

The changing tides are caused by a couple of factors….but mostly the moon. As the moon orbits the Earth, the gravitational force exerts a pull on the side of the Earth closest to the moon and that raises the tides.

This is essentially what 90% of introductory astronomy textbooks say – but it really isn’t the best answer. In fact, that is wrong. If the tides are caused by the gravitational force from the moon, why is there a tidal bulge also on the other side of the Earth (two tides a day)?

Well, if I were invited onto the Colbert Report (not likely) what would I say? In as short of time as possible, I would say:

The Earth and the moon orbit each other. The center of this orbital motion is not the center of the Earth. This causes different parts of the Earth to accelerate different amounts and makes the water move different amounts.

Yes, that isn’t the best explanation. However, it is better than just saying “the gravitational force from the moon”. Here is a longer explanation.

The following is a diagram showing the Earth. The red dot is the center of rotation for the Earth-moon system. The white dot is the center of the Earth.
The Earth is thus an accelerating frame. If you want to, you could represent this acceleration with fake forces. So, the yellow vector arrows represent a combination of the gravitational force from the moon and the fake forces due to the acceleration of the Earth. BOOM. There you will get two bulges.

See. That wasn’t too difficult. Well, it is sort of difficult. The biggest problem is that people that want a simple explanation for something that isn’t so simple.